1. Field of Invention
This invention relates to passenger restraining belt retractors and more particularly to passenger restraining belt retractors for winding up two belts on a single retractor shaft one over the other.
2. Prior Art
Three point passenger restraining devices consisting of lap and shoulder restraining belts are widely used as restraining systems for the purpose of restraining passengers during vehicle emergencies, such as collisions, etc. In these three point restraining devices, the useability and storeability of the restraining belts is improved by the installation of a retractor system which retracts, by means of an applied force, that portion of the restraining belt not used by the passenger and the majority of both belts when the passenger is not using the restraining belt.
In such three point restraining devices, the installation of a separate restraining belt retractor for each of the lap and shoulder restraining belts is considered to be the most effective method of improving the useability and storeability of the belts. However, a restraining belt retractor system which winds up both restraining belts on a single retractor one over the other without injuring the useability or storeability of the belts has been proposed.
As shown in FIGS. 1 and 2, this two belts retracting type of restraining belt retractor is designed as follows:
The lap restraining belt 10A and the shoulder restraining belt 10B are formed by a single continuous belt which is folded back through an opening 12 and in a tongue plate 11. The lap restraining belt 10A and the shoulder restraining belt 10B, which is folded back through an eye in an anchor 14 fastened to the upper portion of the side wall of the vehicle body 13, are rolled up together on retractor 15.
The retractor 15 is fastened to the lower portion of the side wall of the vehicle body 13 and is designed so that the lap restraining belt 10A and the shoulder restraining belt 10B are rolled up on a powered retractor shaft 16 one over the other. The passenger sitting in the seat 17 puts the three point restraining device into use by engaging the tongue plate 11 with the buckle 18 which is anchored at the approximate center line of the vehicle.
The use of such a two belts retracting type of restraining belt retractor system makes it possible to simultaneously extend both restraining belts by pulling either one of the restraining belts from the retractor 15. Furthermore, since one continuous restraining belt is folded back through the tongue plate 11, it is possible to adjust the relative length of each belt so that the lap restraining belt 10A and the shoulder restraining belt 10B are both constantly maintained at an appropriate length. Accordingly, such a system has offered superior useability and handling in spite of the fact that only a single retractor is employed.
In this two belts retracting type of restraining belt retractor system, when one of the restraining belts is extended, the other restraining belt is also simultaneously extended to the same length. Accordingly, the tension acting upon the other restraining belt which is not pulled is weak so that there is the possibility of this belt becoming slack inside the retractor case (as shown by the broken line in FIG. 2). A restraining belt which has thus become slack inside the retractor case injures the handling characteristics and restraining ability of the system and may interfere with the operation of the emergency locking retractor mechanism which automatically stops the extension of the restraining belt during a vehicle emergency.
This invention has been designed with the aforementioned difficulties in mind.